I'd suggest you order yourself a nice prime lens. Being able to adjust your aperture from 1.4 to 2, 2.8, 4, 5.6 and so on and seeing the difference it makes in shutter speed and then comparing the results (DOF) at different apertures after the photos is taken really helps to learn.
Also by limiting yourself to not using a zoom you start to pay more attention to how you frame and compose your shots rather than just sitting in one spot and zooming.
I'd also suggest picking up a hot-shoe mountable speed-light so you can start playing with light and start seeing how one of the most important aspects in photography is light.